The incidence of tremor in Multiple Sclerosis (MS) has been estimated to affect up to 2/3rds of patients. Over half of the tremors involve the upper limb and frequently lead to further disability. Medical treatment of MS tremor is generally unrewarding, although carbamazepine, clonazepam, glutethimide, hyoscine, isoniazid, ondansetron, primidone, and tetrahydrocannabinol have been reported to have some beneficial effect but published evidence of effectiveness is very limited. The investigators' experience to date suggests that many of the upper limb tremors may potentially be responsive to Botulinum toxin injection therapy.